This invention relates to an apparatus and method for modifying the behavior of fish, through a mechanical enhancement of water flow current velocities within a waterway to guide fish from obstructions, such as hazardous areas in a waterway, or to obstruction collection systems. Specifically, it relates to an apparatus and method that modify fish travel patterns by generating a water flow current which creates a velocity head differential in the waterway that fish can sense to guide or direct them during their travels, such as during waterway migration.
Waterway obstructions and other man-made waterway devices pose a risk to migratory fish, contributing to declining stocks of migratory fish and the listing of some fish as endangered species. Such obstructions and related devices may include hydroelectric power plants, municipal water intakes, thermal power plants and irrigation systems.
Recent studies of salmonids have illustrated juvenile fish migration patterns in waterways. Juvenile fish out migrate by orienting, or guiding, on bulk flows of old river channels. These channels, denoting the deepest parts or principal navigational channels of a waterway are referred to as thalwegs, as described in Paul W. Thrush, A Dictionary of Mining, Mineral and Related Terms, Paul W. Thrush Ed., 1968, p. 1131, U.S. Bureau of Mines, Washington, D.C. Adult fish also follow the waterway thalwegs on their migration to their natal streams. Fish suffer trauma and/or extended predation when there is insufficient current to guide them around obstructions or direct them to bypass devices or collection systems that could aid their migration around the obstructions. Fish suffer high mortality rates from such obstructions for a number of reasons; for example: (1) when they come in contact with utility pumps or turbines from the aforementioned devices; (2) when they are subject to thermal water variations induced by nuclear power plants; or (3) when they are ingested or entrained into irrigation systems.
Current fish passage bypass devices or facilities are designed and constructed, essentially, for one of two purposes: (1) for upstream fish passage in a waterway, and (2) for downstream fish passage in a waterway. Upstream fish passage systems, such as fish ladders, are comprised of some type of structure to enable fish to swim up steep inclines. These structures typically utilize a hydrostatic head differential to create a water current at the head of the fish bypass or a fishway. This static head is created by pumped water spilling from a basin or through an orifice or slot. However, this process generates a minor current of limited influence on, and attraction to, the fish and increases migratory delay time while fish search for the entrance to the bypass or fishway. Downstream bypasses or fishways typically consist of barrier devices located at a waterway obstruction, such as at a power plant intake, and some type of physical structure at such obstruction to direct fish around the obstructing facility.
The various devices and methods developed to prohibit entrance to, or direct fish away from, obstructing facility hazards can be categorized as physical barriers or behavioral guidance systems. Physical barriers work by limiting an intake opening size thereby prohibiting entry to fish of a certain size or life stage. These physical barriers include structures such as bar racks, traveling screens, and fixed screens. The main disadvantage to these devices is their cost to construct and maintain. Another disadvantage is that the devices can limit water intake flows, thereby limiting a facility""s power production. These disadvantages ultimately can result in an adverse and unnecessary economic impact on the entity responsible for construction and maintenance of the waterway obstructing facility.
Behavioral guidance systems rely on fish behavioral responses in order to divert fish from a waterway intake or to a collection system device. Current waterway guidance systems include lights, electric fields, turbulence generators, and sound deterrents. Underwater lights, such as strobes, are fish species specific. The visibility of lights to fish, and thus their effectiveness in directing fish in the waterway, varies according to the changing water clarity within the waterway at various times of the year. Underwater electric fields or electric currents in the waterway present a human safety concern. As well, their effectiveness is affected by changing water conductivity. Finally, what is a safe electric current for one species of fish may be deadly for another. Turbulence producing systems, such as air bubble curtains, are energy intensive and are not effective for some species of fish. Sound deterrents are not particularly reliable at present, and an uninterrupted sound barrier to direct fish is difficult to achieve. Furthermore, a sound wave produced by such a system must be tuned for each species of fish and sometimes tuned for separate periods of a life cycle for an individual species of fish.
Persons skilled in the art know the migrational characteristics that are specific to different species of fish, as described (with respect to salmonids in this particular reference) in Adams, Rondorf and Kofoot, and Banach and Tuell, Annual Report 1996: Migrational Characteristics of Juvenile Chinook Salmon and Steelhead in the Forebay of Lower Granite Dam Relative to the 1996 Surface Bypass Collector Tests, 1997, 260 pp., Report to the U.S. Army Corps of Engineers, Contract E-8693151, Walla Walla, Wash. Although this particular reference deals specifically with salmonids, the apparatus and method of the present invention can be applied to any fish species that exhibits migrational characteristics.
Fish ladders associated with a waterway obstruction work by the release of a certain amount of water over the ladders. This water discharge, known as negative static head differential, provides a water current attractive to fish and water in which the fish can swim within the ladder. However, fish ladders are costly due to the loss of power generating revenues by the diversion of water required to operate the ladders. Fish ladders are not particularly effective for the seaward or downstream migration of juvenile fish.
There is limited related art concerning the mechanical generation of water currents to guide or direct fish from obstructive, hazardous areas or to collection systems. Fish ladders, as discussed above, generate currents through water flowing from a higher to a lower elevation.
There is limited related art concerning the mechanical generation of currents to guide fish, as mentioned above. The devices and methods that have been developed are either of the physical barrier or behavioral guidance system type, all having particular problems in their attempts to guide or direct fish. U.S. Pat. No. 4,740,105 to Wollander (1988) uses a screen barrier arrangement system, and U.S. Pat. No. 4,029,049 to Hillier (1977) uses a net barrier system.
Other art related to the mechanical generation of waterway currents for guiding or directing fish, such as U.S. Pat. No. 5,263,833 to Robinson, et al (1993) and U.S. Pat. No. 5,632,572 to Chicha (1997) use floating or buoyant devices with numerous positioning components and members. U.S. Pat. No. 6,102,619 to Truebe, et al (2000) uses a propeller to generate currents to guide fish. These inventions are very complex and energy intensive, and therefore very expensive. Furthermore, they are limited in their flexibility and adaptability to different fish species, and, in the case of propeller generation, potentially harmful to fish that can come into contact with the current generating device. These inventions are limited, as well, in their ability to create enough flow to simulate the necessary waterway bulk flows, or thalweg conditions. In these respects, it can be considered that there is no prior art whatsoever relating to the present invention.
The present invention has many objectives. Among them are the following:
To provide an apparatus for providing within a waterway a fish guidance system comprising: means for generating a velocity head differential in a waterway when said means is installed in a waterway, means for using said generated velocity head differential when said generating means is installed in a waterway to create a current of water within said waterway which fish can sense and use to guide them during their travel through the waterway, and means for directing said generated current of water in said waterway in a desired direction whereby the fish that sense said current of water will travel in the direction of said generated current of water.
To provide a fish guidance system that imitates or duplicates waterway thalweg conditions, or bulk flows;
To provide a fish guidance system that is cost effective;
To provide a fish guidance system that is composed of commercially available components;
To provide a fish guidance system that is reasonably portable and easily and economically deployed.
To provide an apparatus as aforesaid including frame means for supporting in said waterway said means for using said generated velocity head differential to create a current of water within said waterway.
To provide a fish guidance system that is readily and easily adjustable for varying site requirements.
To provide an apparatus as aforesaid in which said frame means includes a base means.
To provide a fish guidance system that is low maintenance;
To provide an apparatus as aforesaid in which the means for using said generated velocity head differential includes: a venturi educator having an eductor tube including a sidewall defining a bore extending there through, said eductor tube having a water intake end and a water discharge end; and a venturi nozzle having water inlet and outlet ends, said venturi nozzle having the outlet end connected in water conducting relationship to the eductor tube at an acute angle directed toward the discharge end of the eductor tube.
To provide an apparatus as aforesaid in which the means for generating a velocity head differential in a waterway includes: a pressure motive water source connected in water conducting relationship with the venturi nozzle thereby creating reduced pressure within said eductor tube so such that during operation of the pressure motive water source water is drawn into the eductor tube at the intake end at a first velocity and discharged at the discharge end at a velocity greater than the first velocity at the intake end.
To provide a method for providing a fish guidance system in a waterway comprising the steps of: generating a velocity head differential; using the generated velocity head differential to create a current of water within a waterway which fish can sense and use to guide them during their travel through the waterway; and directing the current of water so created within the waterway in a desired direction whereby the fish that sense said current of water will travel in the direction of generated current of water;
To provide a fish guidance system which does not require water removal from a reservoir or lake for its operation;
To provide a method as aforesaid in which the step of creating thalweg conditions adjacent the place where current of water is created in the waterway.
To provide a method as aforesaid in which the step of using the generated head differential to create a current of water within a waterway includes: providing a venturi eductor having an eductor tube including a sidewall defining a bore extending there through, said eductor tube having a water intake end and a water discharge end; and a venturi nozzle having water inlet and outlet ends, said venturi nozzle having the outlet end connected in water conducting relationship to the eductor tube at an acute angle directed toward the discharge end of the eductor tube.
To provide a method as aforesaid in which the step of generating a velocity head differential includes: providing a pressure motive water source connected in water conducting relationship with the venturi nozzle thereby creating reduced pressure within said eductor tube so such that during operation of the pressure motive water source is drawn into the eductor tube at the intake end at a first velocity and discharged at the discharge end at a velocity greater than the first velocity at the intake end;
To provide a fish guidance system that does not interfere with, or interrupt, routine plant operation;
To provide a fish guidance system that keeps fish in their natural environment to reduce disease transmission;
To provide a fish guidance system that eliminates the handling of fish;
To provide a fish guidance system that does not require a hydrostatic head differential; and
To provide a method for providing a fish guidance system in a waterway comprising the steps of generating a plurality of velocity head differentials, using the plurality of generated velocity head differentials to create a plurality of currents of water within a waterway to create a velocity curtain which fish can sense and use to guide them during their travel through the waterway; and directing the currents of water so created within the waterway in the same general linear direction whereby the fish that sense said current of water will travel in the direction of generated currents of water.
The aforementioned features, aspects and advantages of the present invention, and further objectives and advantages of the invention will become apparent from a consideration of the drawings and ensuing description.